Building 22x Laser project, help please!

[adgmeijin]

Hi guys im now building a RED burning laser using LG 22x DVD multi-burner drive,here's my ready made host to give you an idea what it looks like, any way im using DDL driver w/ 3ohm resistor without a trimpot. I need your help guys specially the guys who knows well how to make a proper driver for this DVD laser burner; please suggest a resistor value to reach the sweetest spot of (mA)on this project, instead of 3ohm 1/2W resistor what should be the best resistor value to reach the highest but safest power output(mW) for this kind of laser diode,and please estimate the power output(mW) can be made using the suggested resistor value cus i dont have laser power meter yet . im hoping for your effort to help me on this simple project, and i appreciated your ideas here in LPF, thanks.

 

[Bionic-Badger]

It would be best if you learned how it worked yourself, not just rely on what we say. I've attached the circuit diagram for those DDL circuits to the end of this post. How does it work? Look at the examples for the LM317 here (look at the precision current limiter).

After you've figured that out, I think 450mA is about the maximum current those diodes can handle (someone correct me if I'm wrong), though you might want to pull it back a bit to 350mA or so. That circuitboard will also heat-up under all that current, so you'll need to heatsink it.